Textile material having oriented fibers



1 350-404 SR C SEARCH ROOM Aug. 31, 1954 P. BOONE 2,687,673

' TEXTILE MATERIAL HAVING ORIENTED FIBERS Filed April 4, 1949 6Shuts-Shoot 1 IN VEN TOR -Ph/'//,0 Boone A T TORNE Y a- 31, 1954 P.BOONE 2,687,673

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Patented Aug. 31, 1954 UNITED STATES PATENT OFFICE TEXTILE MATERIALHAVING ORIENTED FIBERS 5 Claims.

This invention relates to light-altering materials and more particularlyto light-modifyin bodies, areas, filaments, fabrics or the like forproducing various color and other effects.

It is well known that birefringent or doublyrefracting substances orcomponents in conjunction with light-polarizing means may be employed toresolve a mixture of light into its color components or to produce othervisual effects. It is also known that rotatory-polarizing or opticallyactive substances or elements may be employed with light-polarizingmeans for a generally related objective. The present inventioncontemplates the adaptation of the phenomenons of light polarization,double refraction and optical activity to the textile and related artsand the provision of filaments, fibers, yarns, fabrics and other areasof material capable of producing unusual and attractive color, pattern,luster and variable effects heretofore unknown thereto. Components ofthe invention may be extruded, twisted, folded, spun, coated,interlaced, interwoven, bonded; embedded or otherwise arranged infunctional relation to provide various interference colors and otherqualities. Filaments and yarns of the type to be described herein mayreadily be formed and woven together into fabrics and may also beinterwoven with conventional filaments and yarns. In certain of theconstructions, the interference colors and other effects may be producedby each body or filament alone, and in other constructions they may beproduced through the coaction of a plurality of such bodies or filamentsas, for example, through their cooperation in a fabric. Thus, aconstruction of the invention may broadly be considered as constitutinga self-sufficient, relatively small body or a plurality of coactingbodies forming a larger body or area.

A wide range of uses for materials of the invention is contemplatedinasmuch as their attractiveness and utility are unique, theirmanufacturing cost should not exceed that of known quality textilematerials, and they may be produced by methods generally related toknown methods or by the various methods set forth herein. While certainembodiments of the materials are adapted to produce interference effectsthrough reflection of light, it is presently indicated that those formswhich produce interference colors and other effects through transmittalof light will have greater acceptance and, accordingly, constructions ofthe latter type are in the preponderance among those described herein.

Both reflection and transmittal of light for the above-mentioned andother functions may also be performed by various of the examples as willpresently be described. In other forms of the materials, reinforcing orsupplementary color effects may be obtained by combining known materialssuch as conventional fibers and dyes therewith.

Among principal contemplated decorative and utilitarian uses for thematerials are draperies, curtains, lamp shades, screens, wall panels,window shades, theatrical costumes and properties, and clothing portionsand accessories. While the propensities of light-polarizing anddoubly-refracting or optically active substances to coact for producinginterference colors, and the unusual beauty of said colors have longbeen recognized, substantially no method has been developed heretoforefor making the same available for widespread artistic and utilitarianuses. A principal application has been in the field of microscopy wheredoubly-refracting objects are examined under polarized light to provideinterference color contrast of various regions of the object. Otherapplications such as may have occurred in the field of optics orelsewhere have been restricted to extremely narrow usage or havepossessed limitations which have resulted in their finding little or noacceptance. The marked differences therefrom of products and methods ofthe invention in such considerations as form, performance andadaptability to significant esthetic and utilitarian uses of the generalpublic are believed to substantiate an inventive concept which isinherently broad in scope.

Inasmuch as variation of orientation of components of the inventionproduces a variety of visual effects, it will be seen that theirembodiment in the form of bodies such as filaments and fabrics offers amultiplicity of directions of orientation not similarly obtainable inother structures. For example, the width of materials of the inventionmay be as extensive as that of any presently known fabric, which is tosay that it is limited only by the capacity of current or to-bedevelopedtextile machinery. Continuous lengths of the materials may be formedsimilarly to other known filaments and fabrics. Functional arrangementof the components to obtain predetermined relative orientations thereofmay be adapted to, or facilitated by known procedures of twisting,spinning, coating and stretching filaments and by substantially any typeof weaving, knitting, braiding, netting or other known methods. Thematerials may be formed. to show qualities of drape and stretch in themanner of conventional textile materials and, accordingly, they may bein the form of assemblies capable of being deformed simultaneously insubstantially all directions, curved as well as planar, withoutappreciably affecting inherent or relative orientation of thecomponents.

With reference to the showing of light-polarizing birefringent andoptically active components in the drawings, the vibration directions ofthe light-polarizing components are indicated therein while principalaxes of birefringent and optically active components are generallyintentionally omitted because they could be operatively represented inseveral directions depending upon the characteristics of the components.A principal axis of a birefringent or optically active component,relative to the drawings, may generally be considered, for purposes ofillustration, as extending either transversely or longitudinally, or inboth directions of said component unless otherwise indicated forproducing a predetermined color or other effect, said direction ordirection or directions providing a given angle of orientation thereofrelative to a light-polariz ing component or components which providesan operative assembly. It is to be understood, however, thatmodifications of said relative orientation may exist and moreover thatvarious crystalline aggregations forming structural patterns or a randomdisposition of anisotropic particles or the like may be bonded to orincorporated in the component or material to provide a plurality ofoptic axes extending in a plurality of functional directions.

It is an object of the present invention to provide novel materialshaving attractiveness and utility wherein a wide range of color andother effects are obtainable through means providing controlledinterference of components of light.

Another object of the invention is to provide textile materials such asfilaments, yarns, fabrics or the like wherein a wide and novel range ofcolor and other effects may be obtained.

A further object of the invention is to provide components adapted tothe production of interference colors and other effects either throughtheir combination in bodies such as filaments or the like or in fabrics,or in both.

Still another object of the invention is to provide materials such asbodies, areas, filaments and fabrics or the like whereinlight-polarizing and anisotropic or optically active components arecombined in a predetermined manner for providing interference colors andother effects.

A still further object of the invention is to provide novellight-modifying bodies capable of contributing to or providing, ofthemselves, interference colors and other effects.

Another object of the invention is to provide light-modifying componentsof the character described which are generally adapted to employment intextile materials or the like.

A further object of the invention is to provide materials and componentsof the character described which may readily be manufactured atreasonable cost and which may have wide esthetic and utilitarian appealand, accordingly, many new and significant uses.

Still another object of the invention is to provide materials of thecharatcer described which are capable of producing interference colorsand other effects through portions thereof enabling either transmittalor reflection of light, or both.

A still further object of the invention is to provide novellight-polarizing and birefringent ma.-

terials, and components of the same, which possess new and usefulproperties.

Another object of the invention is to provide novel materials andcomponents of the character described which are capable of producingvariable interference colors and other effects.

A further object of the invention is to provide various means forproducing products of the invention.

Still another object of the invention is to provide general improvementsin the construction of textile materials such as filaments, yarns,fabrics or the like to the end that appearance of such materials may beenhanced.

These and other objects of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingswherein like reference characters refer to like parts throughout theseveral views of which:

Figures 1 through 11 are side elevation views of differentlight-modifying bodies or filaments of the invention;

Fig. 12 is a perspective view of a light-modifying body or filament ofthe invention;

Fig. 13 is a perspective view of another lightmodifying body or filamentof the invention;

Fig. 14 is a cross-sectional view of various forms of light-modifyingbodies or filaments of the invention;

Figs. 15 through 17 are perspective views of various otherlight-modifying bodies or filaments of the invention;

Figs. 18 through 24 are cross-sectional views of various otherlight-modifying bodies or filaments of the invention;

Fig. 25 is a side elevation View of another lightmodifying body orfilament of the invention;

Fig. 26 is a side elevation view, partly in crosssection and with partsbroken away, of a lightmodifying body or filament of the invention whichillustrates the direction or directions of a light ray relative thereto;

Figs. 2'7 through 30 are perspective views of various swatches oflight-modifying fabrics of the invention;

Figs. 31 and 32 are cross-sectional views of light-modifying materialsof the invention com prising combinations of film and other components;

Figs. 33 and 34 are perspective views of lightmodifying fabrics of theinvention which are, respectively, laminated to a curved or sphericalsurface and embedded in a molded product;

Fig. 35 is a diagrammatic representation of apparatus for producing aproduct of the invention;

Fig. 36 is a diagrammatic repersentation of a modification of elementsof Figs. 35 and 38;

Fig. 3'7 is a diagrammatic representation of a modification of elementsof Fig. 35; and

Figs. 38 through are diagrammatic representations of various apparatusfor producing products of the invention.

For a fuller understanding of the constructions of the present inventionand their function, a preliminary consideration of certain of the basicoptics involved is presented herein, with particular reference to thecoacting properties of a plurality of light-polarizing elements; to thecooperation of birefringent and light-polarizing components; and to theinterrelation of rotatory polarizing or optically active elements orsubstances and other light-polarizing means. It is intended that thetheory or examples presented in conjunction therewith,

which must necessarily be limited, shall not be regarded as in any sensedefining the scope of the invention, said theory and examples beingmerely for the purposes of illustration and for furthering anunderstanding of operation of constructions of the invention, presentlyto be described.

As one example related to the invention, let it be assumed that a pairof light-polarizing elements such as a pair of Nicol prisms or dichroicfoils is arranged in optical alignment and that one of said elements maybe rotated with respect to the other, the pair constituting a polarizeranl an analyzer. It is well known that when the vibration directions(vibration planes, polarizing directions or axes) of such elements arecrossed at right angles, components of light transmitted by thepolarizer are removed or extinguished by the analyzer, and that when thevibration directions of both elements are otherwise mutually disposedas, for example, parallel, components of light are transmitted by bothelements, varying degrees of transmittal being obtainable between saidparallel and crossed positions. Let it next be assumed that abirefringent component such as a crystal, a suitable foil, or the like,is positioned between the polarizer and analyzer, with itscrystallographic or optic axis predeterminedly angularly disposedrelative to the vibration directions of said polarizer and analyzer. Aray of light passing through the polarizer is plane polarized andthereby enters the birefringent component vibrating in a givendirection. Upon entering the birefringent component, it is divided intotwo rays, an extraordinary ray and an ordinary ray, each of whichvibrates in a direction substantially at right angles to the other andtraverses the birefringent component with a different index ofrefraction and velocity, a different distance being traversed therebyand a phase difference being introduced therebetween.

Upon emergence from the birefringent component, both of the rays proceedsubstantially along a direct path to the analyzer, while continuing tovibrate at right angles. The direction of vibration of the rays dependsprimarily upon the angular relation existing between the polarizing(vibration) direction of the polarizer and the optic axis of thebirefringent component. Upon entering the analyzer, the extraordinaryray may be said to be broken into two components vibrating substantiallyat right angles, one of which may be considered as an ordinary componentwhich is absorbed or deviated to one side so as to no further beutilized and the other of which is transmitted as an extraordinarycomponent vibrating in a given direction. The ordinary ray, emanatingfrom the birefringent element is resolved by the analyzer into anordinary component which is absorbed or deviated to render the same nolonger functional, and an extraordinary component, vibrating in adirection similar to that of the firstnamed extraordinary component,which is also transmitted by the analyzer.

Thus, it may be said that two extraordinary components are selected andtransmitted by the analyzer, vibrating in the same direction but with aphase difference therebetween because one derives from the ordinary rayand the other derives from the extraordinary ray between which a phasedifference has been produced. as above described. In consequence, thetwo extraordinary components are adapted to interfere and the resultantof their interference may be transmitted light of a given intensity,extinction of light, one or more interference colors or other effectsdepending upon their phase relation or, in other words, dependingsubstantially upon whether reinforcing or destructive interferenceoccurs and to what extent.

The nature of the interference produced may be due to several factors orvariables. Bearing in mind that the phase difference depends in generalupon the difference between the velocities of the ordinary andextraordinary rays in the birefringent component, and that thisdifference varies for light of different wave lengths (of differentcolors) of the spectrum. it will be seen that a resultant interferencecolor, or its diminution or extinction, relates to such variables as thenature of the light source, the retardation properties of thebirefringent component, and the relative orientation of the optic axisof the latter with respect to the polarizing axes or directions of thepolarizing components. It will be understood that the polarizing axes orvibration directions of polarizing components may have some otherangular relation than 90 and may indeed be parallel, provided the opticaxis of the birefringent component forms some suitable angle therewith,to produce interference colors.

The relative retardation of the ordinary and extraordinary rays may bealtered throughout a wide range where the type of birefringent materialemployed permits variation of its thickness, where internal structuralorientation thereof may be varied, and where the relation between theoptic axis thereof and the directions of polarization of the polarizingcomponents may be varied. If a choice of birefringent materials ispossible a further variable is provided. Birefringent components of theinvention may be varied in all of the above respects.

Where A equals the retardation of one ray with respect to the other(expressed in millimicrons or m where t equals the thickness of thebirefringent element or substance; and where m and n2 equal the lesserand greater indices of refraction, respectively, of the two raysemergent from the birefringent element, we have the equation:

A=t(nzn1) The aforesaid two emergent rays have a difference in phasewhich may be termed P. This dilference equals the retardation divided bythe wave length, or

Substituting the equivalent for A, as determined above, it follows thatWhen the retardation is some whole multiple of a wave length, thecomponents of light emerging from the analyzer are equal and opposite inphase and nullify one another. When the retardation consists of halfwave length odd multiples, said components of light are equal and on thesame side of the line of transmission and, therefore, are of areinforcing nature. The re sultant equals the sum of the two componentsand.

the transmitted light is of maximum intensity.

Various birefringent substances or materials are known, some of whichare classified as uniaxial and others as biaxial, both being termedanisotropic. In addition, other substances are designated as rotatorypolarizing or optically active. The latter substances will also beconsidered as anisotropic herein, as components of light are rotated inopposite directions thereby and at different velocities. Materials orsubstances of each category may be employed in products of theinvention, the choice depending upon constructional requirements andoptical properties desired. Different forms of light polarization suchas circular or elliptical polarization will not be treated upon atlength herein since, although they occur in various stages of lightmodification involved in the invention, exhaustive consideration thereofis in no sense essential to an understanding of the opticalinterrelation of elements or the interference results obtainable.

In general, with other variables constant, it may be said that a.uniaxial birefringent material in conjunction with light-polarizingmeans permits extinction of light or the obtaining of complementarycolors through alteration of the axial relationship of said material andmeans. while a combination of an optically active substance andpolarizing means permits continuous color changes throughout the rangeof the spec trum by changing the axial relationship therebetween, eventhough other variables are held constant, the colors being rotated bydifferent amounts. As employed herein, birefringent materials may beconsidered as substances, components, elements or the like, wherein aphase difference is produced in the general manner described in exampleshereinbefore given, and optically active materials may be regarded assubstances, elements, components or the like, wherein light is dividedinto two circularly polarized components thereof, the light vectors ofwhich rotate at different velocities in opposite directions, light ofdifferent wave lengths being thus rotated by different amounts, and aresultant vibration plane being provided.

An extensive number of substances and materials are adapted to beemployed in forming the bodies, areas, filaments, fabrics or the like ofthe invention, said substances and materials being of various degrees ofsuitability according to their properties and according to specificrequirements. Among anisotropic materials which may be utilized informing one or another of the components are the majority of vegetablefibers, animal fibers, mineral fibers and synthetic fibers. other fibersof a generally isotropic nature may also be combined therewith for suchpurposes as providing a support, an interconnection, an additionaloptical property or some other function. Among the vegetable fiberscontemplated are cotton, flax, sisal and other of the seed hair, bastand structural groups. Animal fibers which may be employed comprisevarious hairs, furs, wool and silk. The mineral fiber asbestos may alsobe utilized. Synthetic materials comprising cellulosic, protein andpolymer types may be employed to particular advantage and furthermaterials either existing or to be developed, having birefringent,optically active, light-polarizing, fluorescent or other contributoryproperties may be incorporated in constructions of the invention.Substantially transparent rubber, latex or a synthetic as, for example,Butacite, manufactured by the E. I. du Pont de Nemours Company, PlasticsDivision, Arlington, New Jersey, maybe employed for special usesinvolving elasticity, or elasticity combined with variablebirefringence. Certain of the above materials may be employed function-Glass and ally of themselves while others may coact to produce variouseffects or serve as carriers for various functional substances.

wherein filaments and fibers are employed, long continuous typesconstitute a preferred embodiment as will be apparent from theconstructions shown and described, although short staple fibers andsmall bodies may serve special functions. Thus, synthetic materials ofthe cellulosic and polymer types may be considered as particularlyadapted to employment for forming filament and fabric components of theinvention as well as for coatings or the like which may be appliedthereto, as will presently be described.

Among the synthetic materials contemplated for various specific uses areviscose and acetate rayons, regenerated cellulose, nitrocellulose, ethylcellulose, cellulose acetate, vinyl acetate, nylon, vinyl chloride,vinylidene chloride, polyethylene, polyvinyl acetaL polyvinyl alcoholand other materials, said materials being treated or modified as may berequired to provide special characteristics. Certain of these materialsare known as adapted to be formed into birefringent and light-polarizingelements through various treatments involving their subjection tostretching operations, applications of fields of force, stain. dye. acidand heat treatments or the like. For example, ethyl cellulose,regenerated cellulose, and polyvinyl alcohol may be stretched, undersuitable conditions of temperature or in conjunction with softeningagents, and preferably set to provide birefringent materials as, forexample, to provide a material wherein a high degree of substantiallyuniform crystalline or molecular orientation is accomplished throughoutthe material, said material having, generally, an optic axisconsistently extending in a predetermined direction.

Various controls may be employed for obtaining predetermined diametersor thicknesses of filaments or other components of the invention. Forexample, in extrusion processes'it is known that the rate of deliveringmaterials to a spinneret, the rate of drawing materials away therefrom,and the amount of stretch applied thereto may all be controlled toregulate diameters of filaments. If, for example, a filament is drawn tofour times its original length, it may be reduced to substantiallyone-half its original diameter. Certain of the materials may be colddrawn and others may be stretched in a softened condition, as providedby applications of heat or softening agents. Various forms of spinneretsor extrusion orifices relating to diameter and con tour of extrudedfilaments are well known.

Materials of the above-mentioned type, which may readily be stretchedand elongated and thereby have their thicknesses and internal structureoriented as, for example, to acquire a certain birefringence, areadapted to be formed into bodies or filaments, orto be employed ascoatings therefor of the type contemplated herein. After such bodies orfilaments are formed, they may readily be joined with other componentssuch as light-polarizing bodies or filaments through constructions ofthe invention to provide a predetermined relation of optic andlight-polarizing axes. It will be understood that in addition toproviding predetermined characteristics of birefringence in filamentcomponents of the invention, such qualities as tensile strength,flexibility, durability, resistance to shrinkage or the like may bevaried therein, the stretching process generally improving tensilestrength and flexibility and increasing birefringence.

The properties of birefringent materials relating to theobtaining ofvarious predetermined colors will now be considered more specifically,and, for purposes of illustration, one of the aforementioned generaltypes of such materials which may be embodied in constructions of theinvention will be utilized. Accordingly, let it be assumed that aplurality of such bodies, as, for example, monofilements or coagulatedmultifilaments, uniformly stretched (of constant birefringence), but ofpredeterminedly different thicknesses are arranged in progressive orderof thickness, side by side, between any suitable light polarizerscrossed at 90. Let it also be assumed that the optic axes of thefilaments are all disposed at a predetermined angle relative to thevibration directions of the light polarizers, for example, at 45, thatwhite light is employed and that the filaments and polarizers are fixedas to axial relation.

The relation of retardation, phase difference and wave length has beendescribed hereinbefore. In accordance therewith, the field of viewsurrounding the filaments will appear dark and, assuming certainthicknesses of the filaments, the thinnest filament may, for example,appear bluegray and other filaments, in order of increased thickness,may appear, respectively, white, yellow, orange, orange-red, deep red,violet, indigo, blue, blue-green, green, et cetera. The relationshipbetween interference colors due to monochromatic light and white lightshould be considered. If monochromatic light is substituted for thewhite light source, that filament which is of such thickness as toprovide a retardation of A will cause the vibration components to beequal and opposite and cancel one another out, the filament appearing asa dark band. All filaments which provide a retardation which is a wholemultiple of x cause a similar operation. Conversely, if the filamentsprovide retardations at odd multiples of /2 maximum intensity will occurbecause the vibration components are equal and in the same phase.

Interference colors due to White light are a subtraction of all of thevarious wave lengths of the spectrum from white. Assuming, in view ofthe foregoing, that monochromatic light produces dark bands fordifferent thicknesses of hirefringent materials and maximum intensitiesat intervals intermediate thereof, the difference between the wavelengths at the opposite ends of the spectrum is such that the first darkband for violet occurs almost in the first position of maximum intensityfor red. For violet, the band is approximately 410 m As the wave lengthfor red is approximately 700 m the maximum intensity for red occurs at350 m or 7\. When the thickness and double refraction provide aretardation of 410 m no violet is present in the interference color.Since the maximum intensity for red occurs at or 350 m the percentageintensity at 410 m would be:

X l= 83 percent )\r tropic substance wherein orientation, as obtainedfor example through stretch, is held uniform. If this constant issubstituted in the equation a straight line curve is the result in aninterference color chart. If various thicknesses are assumed, thecorresponding retardation A may be determined directly. If the normalsequence of colors is known, it is possible either to predict the colorof the substance of a given thickness or to ascertain the thickness ofthe substance having a given interference color, provided the axialrelation of the substance is such that 1Z2n1 is a maximum.

In an interference color chart, interference colors with A less than 550m are said to belong to the first order. Violet (A=550 m belongs at theboundary of the first order. From violet A=550 m l to violet A=1128 mthe colors belong to the second order. From violet A=1128 m, to violetA=1652 m the colors belong to the third order. Above the fourth order,colors are not easily separated. The colors at the end of the firstorder and at the beginning of the second order are the most striking andbrilliant. At the end of the fourth order they merge into one another,forming tints of green and pink tending toward grayish white. Thesecolors are distinct from the blue gray, white and yellowish white of thelower first order. Identification of the order of a given color may bedetermined by using a mica plate or the like capable of increasing ordecreasing retardation of an area by about A A (sodium light). Such anincrease or decrease in the lower first or second orders produces a setof colors entirely different from that occasioned by a similar change inhigher orders. For example, in the case of a first-order yellow A= l00In an increase of 175 my. will result in violet A=575 m and a decreaseof the same amount will produce white A=225 m l. The same increase ordecrease in retardation above the fourth order would produce littleperceptible change.

It will be understood that stretching of a filament of the typeconsidered herein, or micellular orientation as obtained throughextrusion of a filament from a die or orifice, or both, may be employedto provide a filament having a predetermined birefringence. It willfurther be understood that increases in stretch produce increases ofbirefringence and decreases in thickness, said increases ofbirefringence generally exceeding accompanying decreases in thickness sothat resultant increases in retardation properties of the filament occurand the interference colors capable of being produced when the filamentis positioned between crossed polarizers may commence in the first orderand proceed through second and third orders, et cetera. The exactcharacteristics for any material may readily be ascertained and thebirefringence and retardation properties thereof be charted. Forexample, a filament of polyvinyl alcohol of .003" thickness may bestretched and set under suitable conditions of heat so as to acquire abirefringence of approximately 0.013 and a reduced thickness ofapproximately .002". When formed into a composite structure such as thatshown in Fig. 3, namely, when positioned between light-polarizingcomponents so that a principal axis of the birefringent filament isdisposed at 45 relative to polarizing directions crossed at a secondorder blue may be provided. A second filament of similar initialthickness may be stretched to acquire a birefringence of approximately0.029 and a reduced thickness of approximately .0015" and, whensimilarly employed with polarizing components, may provide a secondorder reddishpurple. Lesser and greater stretches of said filament couldbe employed to provide, respectively, first or third and higher orderinterference colors. The interference color obtained through a givenamount of stretching depends upon the hirefringence per unit thicknessproduced in a given material and, accordingly, different materials maybe differently elongated to obtain a given interference color.

Light-polarizing components of the nature contemplated herein may be ofany type having properties which contribute satisfactorily to thefunctional qualities required thereof in a given construction of theinvention. Such qualitie involve the production of colors and othereffects and the adaptability of the constructions to be employed in orto constitute products of the type contemplated as, for example, afilament, fabric or other area of material. Several knownlightpolarizing treatments or substances, such as those identified withvarious synthetic plastic materials may appropriately be employed ormodified for use in forming light-polarizing components or portions ofstructures of the invention. A list of such light-polarizing materialsis presented hereinafter. Presently-known polarizing materials aresuitable for employment in constructions of the invention but it is alsoconsidered that the invention comprehends the development of otherpolarizing materials insofar as they are employed in similarconstructions or serve in similar functional capacities.

Polarizing components of the type comprehended herein are considered aspossessing such light-polarizing characteristics or properties that theyare capable of coacting to produce interference colors or the like whenemployed with substantially any birefringent or optically activecomponent or substance having retardation or other properties adapted tocoact with polarizing means for producing perceptible interferencecolors orthe like. Thus the weakest partial polarizing means which canbe employed may be said to be that which, when crossed at 90, is capableof coacting with a birefringent or optically active substance orcomponent to produce a perceptible color or colors substantially at theend of the first order and at the beginning of the second order ofspectra. The strongest or most complete type of polarizing means whichmay so be employed is that which, when polarizing axes thereof arecrossed at 90, produces extinction of light. The most complete type ofpolarizer, when employed with anisotropic materials, is particularlyadapted to provide the most brilliant interference colors. Partialpolarizers and polarizers providing more than 99% extinction, formed ofsynthetic plastic materials are well known. Thus effectivelightpolarizing substances and components of the type contemplatedherein may be considered as comprising a range extending from arelatively weak partial polarizer which transmits components of lightvibrating in a plurality of directions, although preferentially in agiven direction, to a polarizer which may substantially absorb allcomponents of light excepting those vibrating in a given direction. Itwill be apparent that polarizers intermediate of said extremes may beemployed. The well-known Judd unit of color difference may be employedin determining the weakest perceptible color obtainable with a partialpolarizer, as above described, and may also be used in determiningdifferent interference colors produced.

While, in general, the more completely lightpolarizing components mayconstitute a preferred embodiment, certain constructions of theinvention may advantageously employ so-called partially light-polarizingcomponents or a plurality of such partially light-polarizing componentsin superposed or optically aligned relation to provide more fullylight-polarizing components. It is believed that certainlight-polarizing aspects of the invention are such as to involve novelprocesses and products which will presently be described. It will beunderstood that partial polarizers may be employed to provide dilutecolors through their property of transmitting unpolarized as well aspolarized components of light. In general, it may be said thatpolarizing components of the invention are of types possessing suchlight-polarizing properties, form and arrangement in the constructionsas to contribute effectively to the production of interference colorsand other efiects of acceptable quality relative to the uses intended.

Light-polarizing components of the type contemplated herein mayappropriately be formed of substances providing a neutral polarizationof light, that is, they may polarize light substantially impartiallythroughout the spectrum of, for example, white light, or they may beformed of substances providing light-polarization throughout apredetermined restricted band or bands of Wave lengths. It iscontemplated that certain of the light-polarizing components may employlight-polarizing, or light polarizing and other substances, enablingtheir transmittal of polarized light predominantly of certain wavelengths. For example, a polarizing treatment may provide a red, a blueor some other color in the polarizing component whereby the polarizertransmits vibrations of said color preferentially. Or, some tint, dye orthe like may be added to the polarizing component or be provided in acoating or in another component associated therewith to provide apredominant color characteristic in a light-modifying body or filamentof the invention. Where coacting light-polarizing and birefringent oroptically active components are employed for producing interferencecolors of given characteristics, said provision of a dye, tint or thelike may be utilized to provide,

in effect, a blend with interference colors or a I reinforcement of thesame. Where said coacting light-polarizing and anisotropic componentsproduce substantially white light said provision of a dye, tint or thelike may be utilized for providing a dominant color while theinterference resultant is employed for producing a high luster effect.It will be understood that fabrics or other materials comprisingpolarizing components and such tints or dyes may be formed so that lightemanating therefrom will predominantly be colored light as provided bysaid tints or dyes. It is further to be understood that fabrics or othermaterials comprising polarizing and birefringent or optically activecomponents and such tints or dyes may be formed so that light emanatingtherefrom will predominantly be colored light as provided by said tintsor dyes, or some blend thereof with interference colors, if so desired.

Referring to the drawings, Fig. 1 illustrates a compositelight-modifying body l2, such as a fragmentary portion of a compositefilament comprising a light-polarizing core component l4, of anysuitable cross-sectional shape as, for example substantiallycylindrical, having a direction of polarization or vibration directiongenerally indicated by double-headed arrow 16, and a Z twist or spiralof one or more birefringent filament components [8, of a suitablecross-sectional shape, such as substantially round or fiat, formedaround the core. It may be assumed that the structural orientation ofthe birefringent filament components I8 is substantially longitudinal ofsaid components and that the direction or plane of a principal axis ofsaid filament components forms a predetermined angle with saidpolarizing direction l6 of the core as, for example, an angle of 45.

It will be noted that the thickness of core 14 is appreciably greaterthan that of each filament l8, and, accordingly, because filaments l8provide a relatively thin layer around the core, a functionalsuperposition of birefringent twist and light-polarizing core ispresented substantially throughout the composite body when it is viewedfrom any position radially thereof. It is to be assumed that core I6 isof a predetermined diameter and has predetermined light-polarizingproperties. It is also to be understood that birefringent components 18have predetermined diameters and preferably similar internal structuralorientation and are of such thickness as to provide a predeterminedretardation and phase difference between ordinary and extraordinary raystransmitted thereby.

Wherever a twist of components is shown herein, the number and thicknessof said components are contingent upon the relative thickness of thecore and the angle at which the twist is to be wound around the core.Unless otherwise specified, either an S or a Z twist may be employed.Light incident twist [8 passes through the same to core M. It is planepolarized by core 14 and the transmitted components again enter twistl8, at a side remote from the area of incidence, and a difference ofindex of refraction between said components occurs in the mannerhereinbefore described. Composite filament i2 is adapted to be employedwith other filaments of similar or other characteristics in an assemblysuch as a fabric. In said fabric, filament [2 may serve as a cooperativeor coacting body with another light-polarizing means in the productionof interference colors or other effects. Core component [4 mayappropriately be formed as a monofilament or a multifilament ofextruded, coagulated substantially parallel strands of a suitablesynthetic plastic material which has been treated to serve as a lightpolarizer.

Filament components l8 may be formed of any suitable birefringentmaterial such as one of the materials hereinbefore described. It is tobe assumed that the materials employed in composite body or filament l2and in all of the constructions herein are suitably treated to providesatisfactory characteristics of tensile strength, resistance toshrinkage and other qualities which may be required of a fabric or otherarea of material of a type contemplated.

Fig. 2 represents a composite filament 20 of the same general type asthat of Fig. 1 comprising core component 22, having a light-polarizingaxis or direction 24 and an external layer of birefringent filamentcomponents 26. Composite filament 20 differs from filament l2, however,in

14 I that birefringent layer 26 is formed of an S twist. The compositefilaments of Figs. 1 and 2 may advantageously be combined in a fabricas, for example, one filament serving as the warp and the other as theweft or filling, said arrangement enabling, for instance, crossedpolarizing components and parallel birefringent components, as providedby said warp and filling. It will thus be seen that filaments of thewarp and filling coact to produce interference colors or the like.

Fig. 3 shows a composite light-modifying body or filament 28 comprisinga birefringent core com ponent 30 formed of one or a plurality ofcoagulated filaments of the type hereinbefore described, the structuralorientation of said core preferably being substantially longitudinalthereof and a predetermined generally uniform direction of the opticaxis thus being established throughout said core component. A twist orspiral of one or more light-polarizing filament components 32, having adirection of polarization or vibration direction in dicated bydouble-headed arrow 34, is formed around core component 30. Core 30 maypreferably be substantially cylindrical in shape and twist components 32may preferably be generally cylindrical or fiat in shape although othershapes may be employed. It will again be observed that core component 30is of considerably greater diameter than twist components 32 and thusprovides a superposed functional relation of components when viewed fromany position generally radially of the core. The angle at which twistcomponents 32 are formed around core 30 provides a predetermined angularrelation between polarizing direction 34 and the optic axis of corecomponent 30. It may be assumed that core 33 comprises a predeterminedthickness of birefringent material contributing to a given retardationand phase difference between transmitted light components. From a radialviewing position and looking through composite filament 28, it will beapparent that portions of polarizing twist 32 which are locatedgenerally diametrically opposite one another, on opposite sides of thecore, are crossed at angles depending upon the angle of twist, and thatwhen crossed at as generally indicated in Fig. 3, one of the preferredangular relationships therebetween exists. It will further be apparentthat a birefringent component is provided in the form of core 30 havinits internal orientation, and accordingly its optic axis, angularlydisposed relative to said crossed polarizing directions, said angularrelation being generally indicated as 45, which constitutes one of thepreferred angular relationships between the optic axis and polarizingaxes. Light rays incident any given surface portion of twist 32 areplane polarized in passing through the same, are resolved into ordinaryand extraordinary rays having a phase difference by core 30, and aretransformed into componentsvibrating in a given plane by the oppositeportion of twist 32 whereby an interference color is produced. Compositebody or filament 28, accordingly, is a self-sufiicient unit forproducing interference colors and other effects and may be employed in afabric as, for example, the warp, substantially conventional transparentfilaments being suitably employed as filling or vice versa.

Fig. 4 illustrates a composite light-modifying body or filament 36having a twist of substantially fiat, ribbon-like components 33 formedaround a core component 40. The twist may consist of light-polarizingcomponents and the core comprise a birefringent component, or the twistmay be formed of birefringent components and the core consist of alight-polarizing component. Composite filament 36 may thus functioneither in the manner of the filaments of Figs. 1 and 2, or similarly tothat of Fig. 3. It will be apparent that use of ribbon-like component 38permits a decrease in the angle of twist without a proportional increasein the diameter of filament 36. If desired, the twist could beoverlapped to provide different thicknesses of a birefringent layer.

In Fig. 5, a composite light-modifying body or filament 42 which may bealtered dimensionally to vary interference colors or the like is shown.As a preferred embodiment, composite filament 42 may be regarded asgenerally similar to that of Fig. 3 as to the relation of components,with a twist of light-polarizing filament components 44 havingvibration, directions 46 formed around a birefringent core component 48.However, core component 48 is formed of a suitable elastic material,such as a transparent rubber, latex or a synthetic elastic material ofthe type above-described so that, upon stretching said core component asindicated by the arrows, its thickness may be altered and differentretardation properties may, accordingly, be acquired thereby. In amodified form, core 48 could serve as an elastic light-polarizingcomponent and twist 44 could be in the form of elastic birefringentcomponents, preferably bonded to the core whereby, upon stretchingfilament 42, and thus probably rendering the core slightly lessefficient as a polarizer, twist 44 would be stretched obliquely withrespect to its axis and both thickness and direction of internalorientation thereof would be altered, thus afiecting its propertiesrelating to the production of interference colors as hereinbeforedescribed. In a less preferred modification of the first-named elasticembodiment, the twist may also be bonded to the core, provided asuitable elastic polarizing material is used. The firstnamed embodiment,which is preferred, provides a self-sufficient unit for variablyproducing interference colors and, accordingly, it may be combined withsubstantially transparent conventional elastic or essentially nonelasticfilaments to form a stretchable fabric wherein the color and lighttransmission may be varied by stretching and relaxing the same. Thesecond-named or less preferred embodiment would require combination withanother light-polarizing means.

The composite body or filament 50 of Fig. 6 may be considered asillustrating any of the lightmodifying bodies of Figs. 1 through with anadditional layer or twist formed thereabout. For example, it may consistof a birefringent core component 52, a twist of light-polarizingfilament components 54 having a polarizing direction 56 formed aroundthe core, and a twist of substantially transparent surfacing components58 formed around components 54. Surfacing twist 58 may, for example, becolorless and contribute to an appearance of whiteness of a fabric inwhich the filaments are woven when light is reflected from the fabric.Or, twist 58 may comprise a transparent dye or tint for providingreflection of colored light and for coacting with core 52 and twist 54so that interference colors produced by the latter will be modified bythe color of twist 58 and a different resultant color will be obtained.Where core 52 and twist 54 produce a substantially white interferencecolor, twist 58 may be employed to provide some other color which isdominant. Twist 58 may also be utilized to fur- 16 nish a desiredsurface texture and, accordingly, may be twisted more irregularly thanshown. Furthermore, twist 58 may be of a material adapted to receive adesired surfacing treatment which, for example, may be applied to afabric in which the filament is incorporated.

Twist layers 54 and 58 may, however, each consist of partial polarizers,preferably superposed so that their polarizing directions extendsimilarly, the two layers reinforcing one another to provide morecomplete polarization of light. If twist components 54 and 58, aspartial polarizers, serve said curnulative function, it will be apparentthat certain materials which are capable of producing only partialpolarization of light but which have other advantages such asavailability, low cost and adaptability to textile uses may be employedfor the purpose. If, alternatively, composite body or filament isconsidered as comprising a light-polarizing core 52 and a birefringentlayer or twist 54 formed therearound such as shown in Figs. 1 or 4,doubleheaded arrow 56 may be regarded as a direction of internalorientation of the birefringent layer and external twist 58 may beconsidered as a surfacing layer of the general type above described, andeither isotropic or predeterminedly anisotropic for providing somedesired retardation in conjunction with birefringent layer 54. Inconstructions of the invention involving twists, spins, plies, braids orthe like, bonding or fusing of inner superposed surface portions of thecomponents may be desirable to reduce a loss of transmitted light byreflection at said inner surfaces.

Fig. '7 shows a composite light-modifying body or filament 60 having acore component 62, an S twist 64 formed around the core, and a Z twist65 formed around twist 64. Filament may comprise at least any of theconstructions described rclative to Fig. 6 and illustrates an externalreverse twist 56 formed on an underlying twist. Certain structuraladvantages of combinations of s and Z twists are well known in thetextile art. In addition, it will be seen that different angles of twistof layers 64 and 66 may be used for different interference effects ifsaid layers are both birefringent. Double-headed arrow 68 may beregarded as indicating either a polarizing direction of alight-polarizing layer or a direction of internal orientation of abirefringent layer, according to the interpretation of the construction.

Fig. 8 represents a light-modifying body or filament 18 comprisingcomponents 12 and 14 which are twisted together. Component 12 maysuitably have light-polarizing properties, a po-- larizing directionthereof being indicated by double-headed arrow 16, and component 14 maybe composed of a suitable birefringent material having a predeterminedoptic axis. The angle at which said components are twisted together ispredetermined as, for example at 45. superposed portions of thecomponents provide a combination of light-polarizing and birefringentmaterials such that filament 10 may be employed in a fabric, inconjunction with other polarizing means, to produce interference colors.Fig. 8 may also be considered as representing a ply of filaments as, forexample a ply of any of the filaments described herein with a preferablytransparent filament whereby the desirable features of a plyconstruction which are known in the textile art may be achieved. It willbe understood, however, that where the light-modifying filament of saidply is of a type for coacting with another light-modifying filament in afabric (1. e. warp and filling) that an oblique orientation of said plyfilament exists which must be considered with respect to the orientationof the coacting filament. Fig. 8 could also advantageously represent aply wherein both of the filaments comprise a polarizing core and atleast one of the filaments comprises a birefrigent covering as, forexample, 2. ply of the filament of Figs. 1 and 2. Said ply would providea self-sufficient structure for producing interference colors.

Fig. 9 illustrates a fragment of an orientable body 18, suitable forconversion into an oriented body portion 18 which may be employed as,or, in turn, converted into a birefringent component or alight-polarizing component or entity. Body portions 18 and 18 may, forexample, be in the form of a substantially flat ribbon or strip, or asubstantially round or other form of filament. Said portions may,appropriately, be composed of a suitable plastic material such aspolyvinyl alcohol, regenerated cellulose or some other material of thetype hereinbefore described. Body portion 18 may be considered as in agenerally unoriented condition or to be partially oriented as, forexample, in a direction longitudinally of its long axis. To achieve amodified orientation in portion 18, body portion 18 is twisted at apredetermined angle with respect to its long axis, and is then stretchedlongitudinally under suitable conditions of environment, preferablywhile undergoing movement in the direction of arrow 80, stretchoccurring in a predetermined twisted or folded portion thereof generallyrepresented as between a and a. Said stretching of the twisted portionprovides an overall orientation therein substantially in the directionof double-headed arrow 82. After leaving the zone a, a, wherein thestretching occurs, the body is untwisted or unfolded and the untwistedportion 18' possesses an oblique orientation in a direction such as thatrepresented by double-headed arrow 84. It will be apparent that thedirection 84 is primarily de pendent upon the angle at which body 18 istwisted or folded although other factors may be involved.

Two or more bodies of the type of body 18 may be twisted together and asimilar procedure to that above described may be utilized to provideoblique orientation therein, it being apparent that the method ofstretch employed should be such as not to permanently bond the bodiestogether. Body portion 18' may subsequently be treated as, for example,while held taut, to remove any fold marks therein. Furthermore, assumingthe above-described stretch of the material to have been less than saidmaterial is adapted to undergo, a further longitudinal stretch may beapplied to portion 18 without appreciably disrupting the obliquestructural orientation therein, it being apparent that the primaryoblique orientation is well established in the material. Treatments ofheat or other suitable softening agents may be applied to the materialin conjunction with the above-described methods to facilitate the same.Subsequent treatments for hardening, insolubilizing, coating orotherwise treating the material may be applied thereto such asapplications of heat, boric acid or coatings hereinafter described.

In its condition of oblique orientation, body 18 may be employed in anyof various capacities where a birefringent material having said bliqueorientation would prove useful. For example, it may be utilized as abirefringent component in various of the constructions described herein.Assuming body 18 to have such composition or characteristics that whenit is stretched it acquires light-polarizing properties, or maysubsequently be treated to acquire said properties, it will be seen thata polarizing body having a predetermined oblique light-polarizingdirection may thus be formed. In the form of a polarizer, body 18 mayalso be employed as a polarizing component of the present inventionhaving oblique orientation of its polarizing direction. It will beevident that the plurality of oblique orientation angles which may beprovided in birefringent and polarizing components, as above described,when added to longitudinal directions of orientation obtainable by knownmethods of stretch or other processes, and reverse directions of twisthereinbefore described, offer substantially any relative disposition ofoptic axes and light-polarizing directions. Other constructions andmethods relating to orientation of components will also be describedherein. It is to be understood that the above language relative totwisting body 18 is also intended to cover the coiling, folding,spinning or otherwise shaping of the same to achieve a substantiallysimilar arrangement thereof during the stretching process.Alternatively, said twisting or the like may be performed,simultaneously within the portion undergoing stretch.

Fig. 10 illustrates a light-modifying body 86 comprising a twist oflight-polarizing components 88 formed around a birefringent corecomponent 90. While said twist is shown as composed of generally flat,ribbon-like components, said components may be substantially round or ofsome other shape. Fig. 10 is primarily intended to illustrate a possiblerelation of various axes which may exist in a body or filament of theinvention. For example, diametrically opposed light-polarizing portionsare shown as having polarizing directions 92 and 94 which are crossed atwith respect to one another. Birefringent core component 90 isrepresented as having a direction of structural orientation 96 andprincipal axes 98 and I00 which are disposed substantially at 45 withrespect to the polarizing directions 92 and 94.

Fig. 11 illustrates a light-modifying body I02 comprising a plurality ofbraided components I04, I06, and I08, any two of which may appropriate1ybe formed of a light-polarizing core having a layer of orientedbirefringent material formed thereabout. The third of said component maysuitably have merely light-polarizing properties although a birefringentlayer of predetermined orientation could also be formed thereupon.Assuming but two birefringent layers, as above described, one of saidlayers would appropriately be of an 8 type and the other of a Z type.The double-headed arrows H0, H2 and H4 indicate the polarizingdirections of said components I04, I06 and I08. Accordingly, braidedbody I02 comprises a plurality of superposed functional light-polarizingand birefringent areas for producing interference colors wherein arecomprised light-polarizing portions and interposed birefringent portionsof alternately different thickness having suitable axial directions forcoacting with one another. In accordance with the abovedescribedconstruction, the principal axes of superposed birefringent portions mayextend in a similar direction. As shown in Fig, 9 and presently to bamplified, birefringent components having a different relationtherebetween may be employed. Where the third component also has abirefringent layer formed thereabout, it will be apparent that theabove-described alternately different thickness of interposedbirefringent portions may not necessarily exist. The construction ofFig. 11 may also be employed for other obvious purposes as, for example,whenever it is desired to provide an angular relation of one or morecomponents with respect to the longitudinal direction of a body.

Fig. 12 shows a light-modifying component II6 which is adapted topolarize light passing therethrough and which may have alight-polarizing direction H8 or some other light-polarizing directionor directions. Component I I6 is adapted to polarize light which passestherethrough, substantially impartially in any direction. The componentI I6 may be formed of a suitable transparent material I20 havingportions I22 adjacent the surface thereof which may be renderedlight-polarizing by any suitable means, or I20 may represent asubstantially isotropic core material or a non-functionally orientedmaterial which is not adapted to be rendered light polarizing and I22may represent a light-polarizing layer formed around said core.Polarizing portion or layer I22 may appropriately be composed of apartial polarizer whereby light passing through component IIG may bepolarized to a desired degree by passing through substantially oppositeareas of layer I22 and be d ubly D tially polarized to achieve a morecomplete polarization. If deisred, portion I20 may be lightpolarizingthroughout, it being obvious that physically thicker syntheticpolarizers should, in

.generaLlhave less density to equal the performance of thinnerpolarizers.

In another construction relating to Fig. 12 component IIB may comprise alight-polarizing portion having a direction of polarization extendingdifferently from that of double-headed arrow II8 as, for example,portion I20 may be formed as described relative to Fig. 9 and anypredetermined oblique orientation may be provided therein. In saidconstruction, portion I22 may represent either a polarizing portion ofI20 adjacent the surface or a protective coating for an underlyingpolarizing portion. It is to be understood that a protective coating maybe applied to a surface of any of the components described herein or tolayers formed thereupon.

In another modification of Fig. 12, component H6 may comprise anisotropic or a non-functionally oriented transparent core I20 and alightpolarizing coating I22 formed around only a part of itscircumference as, for example to one side of dotted lines D, b, saidpartial coating being provided after incorporation of component I I6 ina fabric, as will presently be described. In still another modification,component II6 may comprise an isotropic or non-functionally orientedcore I20 and a layer I22 composed of an optically active substancecomprising, for example, suitable oriented minute crystals of arotatory, polarizing type, for example, sulphate of strychnia, sulphateof aethylendiamin, sodium chlorate, or a suitable rotatory polarizingamorphous solid such as may be formed from an optically active solution,for example, tartaric acid. An additional protective coating (not shown)or a stabilizing treatment of the optically active layer I22 wouldprobably be required in the lastnamed modification. Although componentH6 is represented as of cylindrical shape, it may have some other shape,as hereinbefore described. Light-polarizing properties of component I I6may 20 be provided by any of the well known methods involvingstretching, applying predetermined fields of force thereto, rubbing,treating with a stain, a gas or an acid, applying heat thereto, or bysome other method.

Fig. 13 illustrates a light-modifying component I24 which is adapted toserve in a birefringent capacity and which may comprise a birefringentcore I26 and a protective coating I28 or a substantially isotropic coreI25 and a birefringent coating l28. The last-named form would permit arelatively thin birefringent portion relative to the overall thicknessof the component. Many suitable birefringent materials would, however,permit their use as filament components without a protective coatingthereon. Although component I24 is represented as round in crosssection,it could be of some other shape as, previously described. A birefringentcomponent could also be formed as a hollow rod or tube to reduce thethickness of the material while providing a relatively large outsidediameter, said thickness contributing to a predetermined phasedifference between transmitted components of light when employed withpolarizing means.

Fig. 14 illustrates a plurality of cross-sectional shapes in whichvarious constructions of the invention, such as light-polarizing andbirefringent components, may be formed. Choice of the same depends uponthe interference effects and other characteristics desired in the fabricor other material. Type 4 constitutes a preferred embodiment for generaluse in the constructions described herein because it is radially uniformand provides consistency, as between components, of one of thevariables, namely, that of thickness which relates to the production ofinterference colors. Type 5 has already been described as particularlyadapted to use as a form of twist. Other forms may be employed where apredetermined selection of other variables, hereinbefore described,permits slight alterations of thickness of birefringent componentswithout appreciably varying the interference colors produced. Wherefunctional components are in the form of coatings, it will be understoodthat said coatings may be substantially uniformly distributed overirregular or other carriers therefor such as types I, 2 and 3. Similarconsiderations are pertinent relative to polarizing components. Forms ofcomponents represented by types I, 2 and 3 may also be employed whereunevenness of interference effects and/or texture are desired. It willbe understood that shapes other than those shown may also be employed.

Figs. 15, 16 and 17 illustrate various forms of compositelight-modifying bodies or filaments comprising core components andsurrounding layers coated thereupon. Subcoats therefor may also beemployed, as required. Functionally, said bodies are substantiallysimilar to bodies and filaments previously described, having a twistformed around a core.

In Fig. 15, a composite light-modifying body or filament I30 is showncomprising a core component I32 and a coating component I34 surroundingsaid core. Core I32 may appropriately represent a light-polarizingcomponent having a predetermined polarizing direction such as I36, andcoating I34 may be formed of a suitable birefringent or optically activematerial having a predetermined direction of orientation such as I38which provides a suitable angular relation of its principal axisrelative to polarizing direction I36, or, if preferred, comprising arandom disposition of birefringent r optically active particles. Theoblique direction I36 may be obtained as through employment of alight-polarizing element of the type described with respect to Fig. 9 asa core, or by a method presently to be described. Coating I34 may thenbe applied and orientation thereof achieved by stretching the compositebody or by applying a field of force to said coating as, for example,while applying the coating or thereafter. The functional opticalrelation of polarizing and birefringent components having a relativedisposition of their axes similar to that above-described has beendescribed hereinbefore. Accordingly, body or filament I30 may beemployed in conjunction with a similar filament, as in a fabric, wherebysaid filaments are capable of coacting to produce interference colors.Or, body or filament I30 may be employed with any suitable polarizingmeans for providing interference colors.

Filament I30 of Fig. 15 may also represent a light-polarizing layer I34having a polarizing direction I38 surrounding a birefringent core I32having a direction of orientation I36. Light, in passing through thefilament is intercepted by two polarizing portions having paralleldirections of polarization and by a birefringent portion having an opticaxis angularly disposed relative thereto, interposed between thepolarizing portions, an arrangement adapted to produce interferencecolors. Alternatively, core I32 may comprise optically active ratherthan birefringent properties.

In Fig. 16, a composite light-modifying body or filament I40 comprisinga core component I42 and a coating component I44 surrounding said coreis shown. Core I42 may comprise a lightpolarizing material having apolarizing direction I46 and coating I44 may suitably be formed of abirefringent material having a direction of orientation I48, or,alternatively, coating I44 may comprise an optically active material. Asa modification, core I42 may comprise a birefringent material having adirection of orientation I46 and coating I44 may comprise a spirallyoriented coating having a polarizing direction I 48. As describedrelative to a twist, a spiral orientation formed around a core providescrossed polarizing axes transversely of the core. The significance ofsaid arrangement of components relative to production of interferencecolors has been described hereinbefore.

Fig. 17 shows a composite light-modifying body or filament I50comprising a core component I52, a coating component I54 surroundingsaid core, a second coating component I56 surrounding coating I54, and athird coating component I58 surrounding coating I56. Core I52 compriseslight-polarizing material having a polarizing direction such as I60.Coating I54 comprises an optically active substance which is preferablypredeterminedly oriented with respect to polarizing direction I60, butwhich may consist of areas or particles disposed at random. Coating I56comprises light-polarizing material having a polarizing direction I62,and coating I58 represents a protective surfacing material. Compositefilament I50 is adapted, of itself, to produce interference colors in amanner hereinbefore described. Filaments of Figs. 15, 16 and 17 couldcomprise both cores and coatings which are elastic to produce effectsgenerally similar to those described with respect to Fig. 5.

Fig. 18 represents, in cross-section, a composite light-modifying bodyI64 of substantially flat or 22 ribbon-like form comprising alight-polarizing layer I66 having a predetermined polarizing direction,and a superposed layer I68 formed thereupon or bonded thereto comprisingan optically active substance. At least portions of the optically activesubstance are so oriented with respect to said polarizing direction asto coact with light-polarizing layer I66 and to rotate components ofplane polarized light entering the optically active substance from thepolarizing layer. Plane polarized light incident layer I68 from anexternal source (not shown) may be rotatorily polarized by the opticallyactive substance and resolved into interference colors by polarizinglayer I66.

Fig. 19 illustrates, in cross section, a composite light-modifying bodyI10 of substantially fiat or ribbon-like form comprising a lighttransmitting layer or core I12 and a surrounding layer or coating I14.Core I12 may comprise an optically active substance and coating I14 maycomprise a light-polarizing material having a predeterminedlight-polarizing direction. At least portions of said substance are sooriented with respect to said polarizing direction as to coact with thelight-polarizing material and to rotate components of plane polarizedlight entering core I12 from coating I14. In turn, a substantiallyopposite portion of coating I14 serves as an analyzer for the rotatedcomponents to provide interference colors. Alternatively, core I12 maycomprise light-polarizing material and coating I14 may comprise anoptically active substance, the optical properties of such aconstruction being similar to those of Fig. 18 excepting that rotatorypolarization occurs for light passing through the body from a sourceeither above or below the same, as positioned in the drawing.

Fig. 20 shows, in cross-section, a composite light-modifying body I16 ofsubstantially fiat or ribbon-like form comprising three functionallayers I18, I and I 82. Said layers may be effectively bonded to oneanother or may consist of a central layer I80 having coatings I18 andI82 applied to both sides, or a central layer I80 having a coating I18applied to one side and a layer I82 bonded to the other side. Thecentral layer may comprise light-polarizing material and the superposedlayers may, accordingly, comprise an optically active substance orsubstances or, alternatively, the central layer may comprise anoptically active substance and the superposed layers may, accordingly,comprise light-polarizing material. At least portions of the opticallyactive substance are so oriented with respect to a polarizing directionof the polarizing material as to produce interference colors. Theoptical properties of the two constructions are generally similar tothose of Fig. 19.

Fig. 21 illustrates, in cross-section, a twist of transparent filamentcomponents I84 bonded to a transparent core I86 by a transparent bondingsubstance I88 such as vinyl acetate or methyl methacrylate. The bondinsubstance I88 may serve several functions. For example, it may beadapted to prevent slippage of the layer of filaments around the coreduring a twisting process and/or after incorporation in a fabric. Or, itmay serve as a barrier to prevent a dye, stain or the like, frompenetrating to underlying portions of the filaments I84 or to thesurface of core I86. The first-named function applies to any of thetwist constructions shown herein, and the second-named function wouldapply when twist I84 is a light-polarizing component. A twist adapted tobe treated to become light-polarizing could thus be stained, dyed or thelike upon exposed portions only, thereby reducing the polarizingportions through which light would pass. A slight diffusing property ofbonding substance I88 could be provided therein, in special instanceswhere a small diffusion of interference colors is desired. Relative tothe general subject of selectively treating certain components ofcomposite products of the invention with a dichroic fluid, aconventional dye or another substance, the construction of Fig. 21serving as an example, it will be understood that twist I84 could befused, coagulated or otherwise bonded to core I86, or that said corecould, for example, be of a material nonreceptive to the fluid, orselectively receptive to the dye, et cetera.

Fig. 22 illustrates, in cross-section, the employment of a suitabletransparent subcoat I63 between surfaces of a composite light-modifyingbody of the invention as, for example, between a core I92 and a coatingI94. The subcoat may serve as a bonding agent or provide an interveningsubstance of predetermined refractive index to improve transmission orreflection of light rays relative to said body.

Fig. 23 shows, in cross-section, a light diffusing coating I96 appliedto a surface portion of a lightmodifying body I98 of the invention, saidcoating being applied, for example, similarly to a method, presently tobe described, of applying a light-polarizing fiuid to a fabric.

Fig. 24 shows, in cross-section, a composite light-modifying body orfilament 200 comprising a spirally oriented coating or twist of filamentcomponents 202 formed around a preferably isotropic core 204, saidcoating or twist being birefringent and potentially light-polarizing andproviding a predetermined crossed orientation of transversely oppositeportions thereof. A protective coating 206 is formed upon a portion oftwist or coating 202, it being assumed that said protective coating hasbeen thus formed after filament 200 has been incorporated in a fabric.Coating 206 may be either temporary or permanent and, if the latter, itis transparent. If temporary, it is' adapted to be dissolved by asuitable organic or inorganic substance. Coating 206 is impermeable to alight-polarizing treatment such as a dye or stain. Upon application of alight-polarizing treatment to the fabric, exposed portions of coating ortwist 202 are rendered light-polarizing while portions thereof coveredby protective coating 206 are unaffected by said treatment. protectivecoating 206 may be dissolved if adapted thereto, as above described. Aconstruction providing a light-polarizing portion and birefringentportion radially superposed therewith is thus formed, the optic axis ofthe birefringent portion being predeterminedly angularly disposedrelative to the light-polarizing direction.

Alternatively, coating 206 may be a permanent reflecting orsemi-reflecting coating so that at least part of the light entering thepolarizing and birefringent portions is reflected substantiallyreversely along its path. In a construction where light passes throughpolarizing and birefringent layers to a reflecting surface and is thusreflected, the birefringent layer serves functionally twice, and thepolarizing layer serves both as a polarizer and analyzer. Core 204 mayalso have predetermined anisotropic properties for coacting with saidbirefringent portions of coating or twist 202. In another modification,core 204 may be omitted After the light-polarizing treatment,

24 entirely and layer 202 may then consist of a twist of one or morecomponents, or a spin of a plurality of components. Where layer 202 isin the form of a coating, several methods of providing an oblique orspiral orientation thereof will presently be described.

Fig. 25 represents a side view of a composite light-modifying body orfilament 20I of a type described with respect to Fig. 24 and comprises2. preferably substantially isotropic core 205 and a twist ofbirefringent components 203 formed. around the core, said twist beingadapted to become light-polarizing when suitably treated. A transparentbonding substance, impervious to a light-polarizing treatment such as astain or dye, may suitably exist between the core and twist, or thetwist may be shrunk tightly upon the core. Directions of orientation ofportions of the twist at opposite sides of the core are generallyindicated by double-headed arrows 208 and 2 I 0. Core 205 may havepredetermined anisotropic properties as stated with respect to Fig. 24.Filament MI is adapted to be employed in a fabric as, for example thewarp, with a similar filament forming the filling. A plurality offilaments 20I may thus be incorporated in a fabric prior to a polarizingtreatment thereof. After the fabric is formed, it may be treated with acoating substance for providing a protective coating over inner facingsurfaces of warp and filling in the manner described relative to Fig.24. Or, inner facing surfaces may be temporarily or permanently bondedtogether so as to be shielded from a light-polarizing treatment. Thepolarizing treatment, accordingly, affects exposed surfaces of thefilaments only and birefringent portions are provided, interposedtherebetween. The relation between optic axes of the birefringentportions and polarizing directions of polarizing portions is adapted toproduce interference colors. The relation between birefringent andlightpolarizing axes may be altered by varying the twist angles of warpand filling filaments and by use of S and Z twists. Use of filamentshaving an oblique orientation such as that described relative to Fig. 9may also be employed for further varying the relation of axes, or acombination of said variables may be employed.

Further referring to the above, a twisted monofilament or multifilamentor a plurality of twisted filaments, as shown in Fig. 8, could similarlybe incorporated in a fabric and subjected to a lightpolarizing treatmentthereafter, provided the filament or filaments are birefringent andadapted to become light-polarizing when treated therefor. Lightpolarizing treatments of a fabric, which obviate the necessity ofcoating or bonding inner surfaces of filaments such as those set forthrelative to Figs. 8 and 25, will presently be described. Self-sufficientbodies or filaments of the type hereinbefore described for producinginterference colors may also be treated for providing theirlight-polarizing properties after incorporation in a fabric, providedtransparent filaments crossed therewith in the fabric are substantiallynonreceptive to the polarizing treatment.

Fig. 26 shows a composite light-modifying body or filament 2I2, partlyin cross-section and with parts broken away. The filament is of a typepreviously described and may thus comprise a birefringent core 2M and atwist of light-po larizing components 2I6, having a direction ofpolarization 2I8, formed thereabout. Fig. 26 illustrates the transmittalof light relative to a filament of the invention wherein, for example,may exist an assembly of components having similar refractive indices ora core with a slight- Ly higher refractive index than the twist. Wheredesired, adjacent surfaces may be bonded, fused or coagulated together,as at 220, to insure optical contact of said surfaces, a bondingsubstance preferably having a similar refractive index to that of twistand/or core components, for maximum transmittal of light. For providingreflection of light at various surfaces, materials of differentrefractive index may be employed as, for example, a core having a lowerrefractive index than the twist. Bonding substances of appropriaterefractive index may also be employed for the purpose as well assemi-reflecting coatings or the like.

Fig. 27 illustrates a swatch of a light-modifying fabric of theinvention wherein self-sufficient filaments 222 for producinginterference colors are employed with preferably transparent filaments224 of any desired type. Filaments 222 may be of any of the formsdescribed hereinbefore which are capable, of themselves, of producinginterference colors and other effects and are shown having crossedpolarizing axes 226, although such a relation of axes is merelyillustrative. Filaments 224 may have various optical properties forcoacting with filaments 222 or for otherwise contributing to the overallappearance of the fabric as, for example, they may be tinted. stronglyreflecting, fluorescent or have some other functional characteristic.Moreover, they may provide some other desired characteristic of thefabric such as a texture effect, fire resistance, stability, strength orthe like.

Fig. 28 represents a swatch of a light-modifying fabric of the inventionwherein filaments 228 and 230 are of a type previously described whichcoact, as warp and filling, to produce interference colors and othereffects. Accordingly, said filaments may comprise a light-polarizingcore and a birefringent layer formed thereabout. Doubleheaded arrows 232and 234 generally indicate the polarizing directions of warp andfilling, respectively.

Fig. 29 illustrates a swatch of a light-modifying fabric whereinfilaments 236 may appropriately be of the type shown in Fig. 28.Filaments 236 may, for example, be employed as warp in which event thefilling 238 may suitably be composed of substantially transparentfilaments such as filaments 224 of Fig. 27, previously described. Afabric of this type may be employed with an external source of polarizedlight for producing interference colors. If filling 238 is birefringent,alternate crossings of the filaments will provide portions havingdifferent retardation properties which will produce differentinterference colors from other portions. Two fabrics of the type shownin Fig. 29 could be bonded together, with either a parallel or angularrelation of the polarizing directions thereof, to provide a compositefabric for producing interference colors. Filaments 236 may havepolarizing directions 240 or I another direction, as hereinbeforedescribed.

Fig. 30 shows a swatch of a light-modifying fabric with warp and fillingcomprising coacting filaments 242 and 244 having light-polarizing coresand birefringent surrounding layers for producing interference colors.The warp and/or filling also comprise preferably transparent elasticfilaments 246. When the fabric is stretched as, for example, on thebias, the axial relation between filaments 242 and 244 is altered,providing different interference color effects and differenttransmission of light according to differences in the angular relationof said axes. Alternatively, filaments 242 and 244 may belightpolarizing, without birefringent coatings, for altering lighttransmission only, in which instance a tint or dye may be incorporatedtherewith for providing a constant color to light of variable intensity.It will be apparent that elastic filaments 246 may also thus be tintedor dyed. Elastic light-modifying filaments of the type describedrelative to Fig. 5 may also be employed in the fabric of Fig. 30 inplace of either filaments 244 or 246, or both.

Figs. 31 and 32 illustrate light-modifying bodies or filaments of typesdescribed herein, which are associated with a film or other component orcomponents to form composite structures. In Fig. 31, a plurality of saidlight-modifying bodies 252, capable of producing interference colors,are formed into a fabric or the like with a plurality of preferablytransparent filaments 254 and said fabric is bonded by a transparentadhesive substance 256 to a film component 258. Film component 258 maybe of a relatively nondeformable type or may have pronounced qualitiesof drape. Said film component may be transparent, translucent,diffusing, dyed or have some other quality according to the intended useof the structure. Alternatively, film 258 may be in the form of a fabricor some other material having generally similar optical qualities tothose described relative to the film. In another modification filaments252 and 254 may be of the type, above described, which coact to provideinterference colors In a further modification, at least one of filaments252 and 254 may comprise a lightpolarizing core and a. layer ofbirefringent or optically active material and film 258 may compriselight-polarizing properties, the polarizing axes of the filaments andfilm being suitably oriented. In still another modification, film 258could comprise both light-polarizing and birefringent or opticallyactive properties while at least one of filaments 252 and 254 could belight polarizing. Other modifications will readily be apparent in viewof various constructions described herein. The fabric may be embedded ina transparent film or laminated between film components. In the lastnamed form, the lightmodifying bodies could be self-sufficient forproducing interference colors or could be merely birefringent oroptically active bodies, the film components being at leastlight-polarizing.

Fig. 32 shows a plurality of light-modifying bodies 250, havingself-sufficient or coacting properties of the type describedherein,.bonded by a transparent substance 262 to a film component 264.Said bodies may be oriented, as generally indicated, or may be disposedat random on the surface of the film. Substantially all of themodifications described relative to Fig. 31, omitting those requiringfilaments 254, are applicable to the construction of Fig. 32. It will beapparent that filaments of the present invention may be severed to formshort staple fibers or abbreviated bodies for use in conjunction with afabric, film or other material, in the general manner above described.Accordingly, they may be bonded to or embedded in various materials formany purposes where the production of interference colors is anobjective. It is also to be understood that other fabric constructionscomprising filament components of the invention may be incorporated withfilm materials. The invention also contemplates the provision of anartificial fabric formed of a film-like material comprisinglight-polarizing and birefringent or optically active components havingprincipal and polarizing axes suitably disposed relative to one anotherfor producing interference colors in the manner described herein. Saidmaterial could be formed of thin laminae or could readily be formed bythe method described relative to Figs. 9 and 35. The artificial fabriccould comprise an embossed, etched, printed, flocked or otherwisetreated surface to generally resemble a fabric, or it might have alaminated or embedded netting or the like, or other internal structurefor providing a substantially similar resultant. The interferencecolors, which would generally be visible, could be extinguished whereinsuch constructions provided opaque lines of demarcation, or could bedifferently visible, due to diffraction or other effects, wheretransparent or translucent lines of demarcation were provided. Theartificial fabric could have pronounced qualities of drape or berelatively nondeformable, according to desired characteristics thereof.

Figs. 33 and 34 illustrate the adaptability of light-modifying fabricsof the type described herein to be draped in various contourssubstantially without affecting the orientation of their light-modifyingcomponents. Fig. 33 represents such a fabric 266 laminated to aspherical surface 268. Fig. 34 illustrates a draped fabric 210 of saidtype embedded in a molded transparent plastic body 212 or the like. Thedouble-headed arrows indicate the presence of vibration directions oflight-polarizing materials rather than any specified direction thereof.Where the fabrics are draped, so that curved areas thereof are formed,various merging interference effects will be visible to an observerwhile viewing said areas from any position, said effects relating togradations of color and luster and being unobtainable in anyconventional fabric. As employed in Fig. 34, a fabric of the inventionmay be deformed according to the requirements of a molded product forproducin interference colors therein. The fabric may also serve tostrengthen the product in a known manner.

Fig. 35 is a diagrammatic representation of apparatus for forming alight-modifying body of the type shown in Fig. 9. Means such as a spool214 releasably holds a supply of a filament, strip or ribbon oforientable transparent plastic material 216. The material 216 is of atype adapted to be rendered birefringent after undergoing stretch, or tobe converted into a polarizer when stretched. Or. material 216 could beof a preliminarily treated type which is adapted to be converted into apolarizer by a stretching process. The material is drawn betweenpreferably freely rotatable pressure rollers 218 and is then twisted orfolded in a given direction and to a predetermined degree as by twistingor folding means 280. It then passes, in twisted or folded form betweenpowered pressure rollers 282 and is subjected to softening means, asrequired. such as heat-applying means 284. Thereafter, it passes betweenpowered pressure rollers 286, which rotate at a predeterminedly greaterspeed than rollers 282, so that the twisted or folded material ispredeterminedly stretched in the area between rollers 282 and 286,internal orientation being longitudinal of the twisted material as awhole, as shown in Fig. 9. After leaving rollers 286, the material isuntwisted or unfolded by untwisting or unfolding means 281 and anoblique orientation, as indicated by double-headed arrow 288, isprovided therein. The material is then drawn between pressure rollers290, which may appropriately be powered to rotate at a more rapid speedthan rollers 286, to take up the slack of material 216 produced byuntwisting the same. The material is then taken up by means such aspowered spool 292. Instead of being drawn from spool 214, the materialmay be supplied from an extruder 294, shown diagrammatically in Fig. 36,said extruder being suitably positioned to the left of dotted line 0-0(Fig. 35). Alternatively to passing from rollers 290 to take-up spool292, the material may be directed to a coating device 296 (Fig. 3'1),said device being suitably positioned to the right of dotted line d--d(Fig. 35). Element 296 may appropriately comprise guide rollers 298 and299 and a container 300, holding a suitable coating substance 302 which,after its application to material 216, is adapted to be renderedbirefringent by stretching means 304, 306, and 308, which are similar infunction to means 282, 284, and 286 but which may apply a differentstretch to the coated material as, for example, a lesser stretch. Thematerial is then taken up by means 310. It will be understood that ifmaterial 216, as supplied to coating device 296, is of a form wherebythe first stretching procedure performed by elements 282, 284 and 286,or said procedure plus a lightpolarizing treatment, render the materialpolarizing, that the coating and stretching means of Fig. 37 complete acontinuous process of forming a body, such as a strip or filament,comprising a light-polarizing component having an oblique orientation,with a birefringent layer having, for example, longitudinal orientation,coated upon the light-polarizing component. Said light-polarizingtreatment could be provided by means 362 of Fig. 39, presently to bedescribed.

Further relative to Fig. 35, if a body such as a strip or filamentcomprising an obliquely oriented central portion or core with apolarizing layer having a different orientation formed thereupon isdesired, a modification of Fig. 35 for forming the same is as follows.Material 216 is rendered birefringent with an oblique orientation bytwisting and stretching means of Fig. 35, already described. Means ofFig. 3'1, inserted at d-d of Fig. 35, may be assumed to provide acoating of potentially light-polarizing substance 302 upon material 216,which is hardened sufficiently for stretching upon leaving tank 300. Thecoated body is stretched by means 304, 306, and 308 to a degree whichdoes not disrupt the oblique orientation of material 216 but whichprovides a generally longitudinal orientation of coating 302. Polarizingtreatment means, such as means 362 of Fig. 39, may then be employedprior to taking up the body upon means 3 l0. Alternatively, material 216may be supplied to coating device 296 either after said obliqueorientation has been provided therein or without having been subjectedto the twisting and untwisting means, namely, with means 280 and 281removed from the apparatus, in which latter instance material 216 wouldhave a longitudinal orientation. Coating 302 could consist of either ofthe aforesaid types of orientable material which are adapted to beoriented when hardened and stretched. By spreading the position of theelements, twistin and untwisting means 280 and 281 could, respectively,be repositioned before and after stretching means 304, 306 and 308.Accordingly, material 216 would be provided with a given orientation, asabove described, and the coating there-

